1. Field
The present embodiments relate to a thin film magnetic head that has a solenoid type recording coil.
2. Related Art
Generally, a recording element portion of a thin film magnetic head includes a magnetic material layer that is formed of a magnetic material. A thin film coil induces a recording magnetic field to the magnetic material layer. A magnetic gap layer is formed at a front end of the magnetic material layer. Magnetic information is recorded on a recording medium by a leakage magnetic field from the magnetic material layer through the magnetic gap layer at a surface that faces the recording medium.
Recently, a solenoid type thin film coil that is wound around a magnetic material layer as a core such that a three-dimensional space around the magnetic material layer is efficiently used has been developed, thereby reducing the size of a recording element portion. The solenoid type thin film coil includes a lower coil wire group that has a plurality of coil wires formed below the magnetic material layer, an upper coil wire group that has a plurality of coil wires formed above the magnetic material layer, and a coil contact layer that electrically connects end portions of individual coil wires of the lower coil wire group and the upper coil wire group. The solenoid type thin film coil may be exemplarily formed according to the following process.
First, a lower coil wire group is formed by arranging a plurality of coil wires formed of, for example, Cu, to extend in a track width direction below the magnetic material layer in a height direction. A coil insulating layer is formed to bury the lower coil wire group and their pitches. A part of the coil insulating layer is removed so as to expose both end portions of the individual coil wires of the lower coil wire group, and a coil contact layer group is formed on both end portions. At the same time, an auxiliary yoke layer is formed so as to be magnetically connected to the magnetic material layer.
Each space between the coil contact layers of the coil contact layer group and each space between each coil contact layer and the auxiliary yoke layer are buried with an insulating resist, and an alumina is formed on the insulating resist so as to planarize an upper surface of the auxiliary yoke layer. A magnetic material layer is formed on the auxiliary yoke layer, and the upper coil wire group is formed on the magnetic material layer through a coil insulating base layer. Both end portions of the individual coil wires of the upper coil wire group are connected to the lower coil wire group through the coil contact layer.
JP-A-8-7222 is an example of the related art.
However, in the known solenoid type thin film coil, since the space between the coil contact layers and the space between each coil contact layer group and the auxiliary yoke layer are buried with an insulating resist layer and alumina is formed on the insulating resist layer, if the thin film coil generates heat, the insulating resist expands, which causes the recording element portion to protrude toward the surface that faces the recording medium.
In the related art, if the recording element portion protrudes toward the surface that faces the recording medium, the protruding portion may damage the recording medium or the recording element portion itself may be damaged. Also in the related art, if the upper surface of the auxiliary yoke layer is planarized by a CMP processing, resist smear may occur. In order to avoid the resist smear, alumina may be used to bury the space between the coil contact layers. Since the coil contact portion has a narrow pitch gap with respect to its thickness (an aspect ratio is small), it is difficult to completely bury the space between the coil contact layers with alumina, and pores may occur.